METHOD AND APPARATUS FOR ELONGATION OF FILM

摘要

An apparatus for stretching polymeric film is disclosed wherein a heating unit is located slightly above and between the parallel tracks of a tenter frame and wherein the heating unit includes an air duct with an air entrance opening and a series of apertures directed between the tenter frame tracks wherein the air duct is separated, by internal intermediate walls, into adjacent isolated zones extending parallel with the tracks of the tenter frame and wherein each isolated zone includes a heater. Air introduced into the duct is conducted through the zones where it is heated and directed through the apertures onto a web of polymeric film moving in the tenter frame prior to stretching.